1. Field of the Invention
The present invention relates to a steering wheel in which a wooden member is mounted on a metal core.
2. Description of the Related Art
A steering wheel for a vehicle has, for example, a boss which is fixed to a steering shaft. The boss is connected via spokes to an annular metal core. Wooden members are mounted on areas of the metal core for the purpose of decoration and the like. The wooden member is formed by a pair of wooden pieces made of so-called laminated wood. One of the pair of wooden pieces is disposed at the front side of the steering wheel and the other is disposed at the back side of the steering wheel.
The pair of wooden pieces are bonded with (adhered to) each other so that the wooden member is mounted on the metal core to surround the metal core.
In such a steering wheel, however, warping of the wooden pieces may be caused by changes in temperature or changes in the amount of moisture (or dryness) in the wooden member. Since the degree of warping of each wooden piece is mutually different, load is applied to the area at which the wooden pieces are bonded together. As a result, there is a possibility that the pair of wooden pieces may partially separate from each other.
In addition, in a case in which the wooden member is mounted where the metal core is connected to the spoke, it is necessary to form an insertion hole in the wooden member to insert the spoke therein. As a result, there is a possibility that the strength of the wooden member in the region around the insertion hole may be lowered.
Further, a problem arises in that, the more the wooden member is disposed with its grain extending in the radial direction of the metal core, the lower the elasticity of the wooden member becomes.
Furthermore, at a vicinity of the surface at which the wooden pieces of the wooden member are bonded together, there is a problem in that the grain of each wooden piece may be misaligned, or the woodgrain pattern and color of the wooden member suddenly change, and the appearance of the wooden member is compromised.
When a plurality of wooden members is respectively mounted at a plurality of areas on the metal core, unless the woodgrain pattern and color of the wooden member are integrated, the appearance of the whole steering wheel will be compromised.
In view of the aforementioned facts, an object of the present invention is to provide a steering wheel in which the strength of a wooden member is enhanced and the appearance of the wooden member is improved.
A first aspect of the present invention is a steering wheel comprising: a substantially annular metal core; and a wooden member comprising a plurality of wooden pieces, the wooden pieces being formed from a pure wooden material and bonded together to surround a part or the whole of the metal core when mounted on the metal core; wherein the wooden pieces are formed from a single pure wooden material, and the wooden pieces that are bonded together are formed from adjacent sites of the single pure wooden material.
In the steering wheel relating to the first aspect of the present invention, a plurality of wooden pieces forming a wooden member are bonded together so that the wooden member is mounted on the metal core to surround a part of or the whole of the metal core.
In this steering wheel, the plurality of wooden pieces are formed from a single pure wooden material (a wooden material to which, after natural wood is cut and processed to be a predetermined shape, special processing (for example, laminating and the like) is not administered), and the wooden pieces which are bonded together are formed from adjacent sites of the pure wooden material. Therefore, the degree of warping of each wooden piece caused by changes in temperature or changes in the amount of moisture (or dryness) in the wooden member is made uniform between the wooden pieces bonded together. As a result, even if the wooden pieces warp, because they wrap in the same way, separation of a plurality of wooden pieces can be prevented due to separation load, which separates the wooden pieces, applied to the surface at which the wooden pieces are bonded together not being applied. Thus, the strength of the wooden member can be enhanced.
In addition, since the wooden pieces which are bonded together are formed from adjacent sites of the pure wooden material, misalignment of the grain of the wooden pieces, abrupt changes in the color and wood-grain pattern of the wooden member, is prevented from occurring at the bonding surface at which the wooden pieces are bonded together. Therefore, the appearance of the wooden member can be improved.
A second aspect of the present invention is a steering wheel comprising: a substantially annular metal core; and a plurality of wooden members, the wooden members being formed from a single pure wooden material and mounted on a plurality of areas of the metal core.
In the steering wheel relating to the second aspect of the present invention, a plurality of wooden members are respectively mounted on a plurality of areas of the metal core, and each the wooden member surrounds a part of or the whole of the metal core.
In this steering wheel, since the plurality of wooden members are formed from a single, pure wooden material, the woodgrain pattern and color of the wooden member are integrated. Therefore, the appearance of the entire steering wheel can be improved.
A third aspect of the present invention is a steering wheel comprising: a substantially annular metal core, the metal core being mounted via at least one spoke to a boss, the boss being fixed to a steering shaft of a vehicle; and a wooden member formed from a wooden material, the wooden member being mounted on the metal core to surround a part of or the whole of the metal core, wherein thickness of the wooden member where the metal core is connected to the spoke is larger than a thickness of the rest of the wooden member.
In the steering wheel relating to the third aspect of the present invention, the boss, which is fixed to a steering shaft of a vehicle, is connected via spokes to an annular metal core, and the wooden member is mounted on the metal core to surround a part of or the whole of the metal core.
In this steering wheel, the thickness (in a metal core radius direction) of the wooden member at the area where the metal core is connected to the spoke is made larger than that of the rest of the wooden member. Therefore, the strength (the breaking strength against external forces) of the wooden member at the area where the metal core is connected to the spoke can be enhanced.
A fourth aspect of the present invention is the steering wheel according to any one of first to third aspects, wherein the wooden member is disposed such that the grain thereof extends vertically with respect to the radial direction of the metal core.
In the steering wheel relating the fourth aspect of the present invention, since the wooden member is disposed such that the grain thereof extends substantially vertically with respect to the radial direction of the metal core, the strength of the wooden member can further be enhanced.
A fifth aspect of the present invention is the steering wheel according to any one of first to fourth aspects, wherein the wooden members are disposed in a symmetrical manner relative to a vertical plane that extends through the center of the metal core in the longitudinal direction of the vehicle.
In the steering wheel relating to the fifth aspect of the present invention, the wooden members are disposed in a symmetrical manner relative to a vertical plane which extends through the center of the metal core in the longitudinal direction of the vehicle. Therefore, the weight of the wooden members disposed at the left side of the vertical plane is substantially equal to the weight of the wooden member disposed to the right side of the vertical plane. As a result, balance (steering performance) of the steering wheel in the direction of rotation thereof can be improved.
As the steering wheel relating to the second aspect of the present invention, in the case in which a plurality of wooden members are formed from a single, pure wooden material, the density of each wooden member is made uniform, and, therefore, balance (steering performance) of the steering wheel in the direction of rotation thereof can be particularly improved.
A sixth aspect of the present invention is the steering wheel according to the first aspect, wherein the plurality of wooden pieces are formed by the singular wooden material being cut at a cutting plane so as to form bonded planes thereof, and the plurality of wooden pieces are bonded together at respective bonded planes.
In the steering wheel relating to the sixth aspect of the present invention, the plurality of wooden pieces are formed by the singular wooden material being cut at the cutting plane so as to form bonded planes thereof, and the plurality of wooden pieces are bonded together at respective bonded planes. Therefore, with the wooden pieces, the degree of warping in each of the wooden pieces caused by changes in temperature or changes in the amount of moisture (or dryness) in the wooden members is made uniform (coincidence) between the wooden pieces. At the same time, misalignment of the grain of each wooden piece, changes in the color and wood-grain pattern of the wooden member, is prevented from occurring at the vicinity of the bonding surface at which the wooden pieces are bonded together.